title: Assessment of pulmonary artery pulse wave velocity in children: an MRI pilot study.
abstract: OBJECTIVE
  To assess the feasibility of measuring pulmonary artery (PA) pulse wave velocity (PWV) in children breathing ambient air and 12% oxygen.
  
  
  METHODS
  Velocity-encoded phase-contrast MR images of the PA were acquired in 15 children, aged 9-12years, without evidence of cardiac or pulmonary diseases. PWV was derived as the ratio of flow to area changes during early systole. Each child was scanned twice, in air and after at least 20minutes into inspiratory hypoxic challenge. Intra-observer and inter-observer variability and repeatability were also compared.
  
  
  RESULTS
  PA PWV, which was successfully measured in all subjects, increased from 1.31±0.32m/s in air to 1.61±0.58m/s under hypoxic challenge (p=0.03). Intra- and inter-observer coefficients of variations were 9.0% and 15.6% respectively. Good correlation within and between observers of r=0.92 and r=0.72 respectively was noted for PA PWV measurements. Mean (95% limit of agreement) intra- and inter-observer agreement on Bland-Altman analysis were -0.02m/s (-0.41-0.38m/s) and -0.28m/s (-1.06-0.49m/s).
  
  
  CONCLUSIONS
  PA PWV measurement in children using velocity-encoded MRI is feasible, reproducible and sufficiently sensitive to detect differences in PA compliance between normoxia and hypoxia. This technique can be used to detect early changes of PA compliance and monitor PAH in children.
authors.affiliation: Department of Child Health, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Chuen Y
authors.initials: CY
authors.lastname: Poon
authors.forename: Julie M
authors.initials: JM
authors.lastname: Edwards
authors.forename: C John
authors.initials: CJ
authors.lastname: Evans
authors.forename: Ashley D
authors.initials: AD
authors.lastname: Harris
authors.forename: Beverly
authors.initials: B
authors.lastname: Tsai-Goodman
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Bolton
authors.forename: John R
authors.initials: JR
authors.lastname: Cockcroft
authors.forename: Richard G
authors.initials: RG
authors.lastname: Wise
authors.forename: Sailesh
authors.initials: S
authors.lastname: Kotecha
mesh_terms: D001783:Blood Flow Velocity; D002648:Child; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000503:physiopathology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D010865:Pilot Projects; D011651:Pulmonary Artery / Q000033:anatomy & histology / Q000503:physiopathology*; D011652:Pulmonary Circulation; D011673:Pulsatile Flow; D063177:Pulse Wave Analysis / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059289:Vascular Stiffness
keywords: Children; Hypoxia; Pulmonary artery; Pulse wave velocity; Velocity-encoded MRI